Mercury

Mercury is the first planet in the Sol system.

Features
Mercury is a very hot planet. It hardly even has an atmosphere, and it is gray and barren, only slightly bigger than Earth's Moon. And it is a planet of a million impact craters.

At one point in the planet's history, a race of tall, red-skinned insectoids made a colony on Mercury then millenia later Mercury's moon, Murculendsia. (implying that this is in the far future as currently Mercury has no moon.)

Mercury fell into the sun in 4,009,970.